Field of the Invention
This document relates to an organic light emitting display device and, more particularly, to a hybrid organic light emitting display device having a stack structure allowing for a soluble process and a deposition process.
Description of the Related Art
An organic light emitting display (OLED) device is an electronic device emitting light in response to a potential applied thereto. A structure of the OLED device includes an anode (positive electrode), an organic electroluminescence (EL) medium, and a cathode (negative electrode). In general, the organic EL medium disposed between the anode and the cathode includes a hole transportation layer (HTL) and an electron transportation layer (ETL). Holes and electrons are recombined in the ETL near the interface of HTL/ETL to emit light. Tang et al. describes a very effective OLED using a structure including the foregoing layers in the document [“Organic Electroluminescent Diodes”, Applied Physics Letters, 51, 913 (1987)] and U.S. Pat. No. 4,769,292 which was generally assigned.
OLED devices have various structures. In a 1-stack soluble hybrid OLED device illustrated in FIG. 1, R, G, and B are realized by forming a hole injection layer (HIL), an HTL, and an emission layer (EML) through a soluble process (or a solution process) and an ETL/electron injection layer (EIL), and a cathode through thermal evaporation. This OLED device has a limitation in efficiency, power consumption and color coordinate adjustment due to 1 stack. Also, after the EIL is vacuum-deposited, when the EIL is exposed to normal pressure and subjected to a soluble process, in spite of an N2 atmosphere, an element is damaged, which negatively affects efficiency and lifespan, and thus, it is impossible to form a 2-stack OLED device with this scheme. In particular, when the ETL and EIL, which are vulnerable to moisture, are exposed again to normal pressure after vacuum-deposition, element efficiency and lifespan characteristics may not be desirable in spite of the N2 atmosphere.
A 2-stack white OLED device illustrated in FIG. 2 generally uses a scheme of implementing white through a stacked structure of blue stack/yellowish green stacks and subsequently transmitting the same to R, G, and B color filters. The 2-stack white OLED device is superior to the 1-stack OLED device in terms of power consumption and luminance, however, efficiency loss due to the use of color filters and color shift according to driving are problematic.